The DEXD/H-box RNA Helicase DDX19 Is Regulated by an
α-Helical
Switch*S⃞

Abstract

DEXD/H-box RNA helicases couple ATP hydrolysis to RNA remodeling
by an unknown mechanism. We used x-ray crystallography and biochemical
analysis of the human DEXD/H-box protein DDX19 to investigate its
regulatory mechanism. The crystal structures of DDX19, in its RNA-bound
prehydrolysis and free posthydrolysis state, reveal an α-helix that
inserts between the conserved domains of the free protein to negatively
regulate ATPase activity. This finding was corroborated by biochemical data
that confirm an autoregulatory function of the N-terminal region of the
protein. This is the first study describing crystal structures of a
DEXD/H-box protein in its open and closed cleft conformations